To improve process control for some semiconductor manufacturing processes, optical metrology and substrate inspection systems are used to measure and quickly provide feedback for real-time control of the processes. Metrology and substrate inspection processes in semiconductor manufacturing, however, are vulnerable to Airborne Molecular Contamination (AMC) as well as moisture within the environment. Additionally, the substrates themselves are also vulnerable to AMC and moisture in the environment, which may produce contaminants on the surface of a substrate or form film growth or corrosion/oxidation. Moreover, the use of AMC filtration may reduce film growth rate, but does not address humidity control effectively enough to prevent corrosion/oxidation.
Purge systems are sometimes used to protect the metrology and substrate inspection systems and/or substrates under test. By way of example, purge systems sometimes use a purged chamber into which a purge gas or clean dry air is provided. Use of purged chamber, however, requires near vacuum chamber sealing integrity to the atmosphere, and significant safety controls to protect service personnel from asphyxiation hazards. Moreover, a significant amount of purge gas or air may be required to adequately purge a chamber. Other purge systems provide a purge gas or air to the beam path of the optical metrology or inspection device. Thus, purge gas or air contacts limited areas of the substrate during testing, but the remainder of the substrate may still be exposed to the atmosphere including AMC and humidity. Accordingly, improvements over conventional purge systems are desired.